This should be an easy question to answer...I've been able to create a variety of ad banners using Flash Catalyst but none of the online tutorials show how to link the ad banner to a URL...i.e. when someone clicks on the banner. I don't like the idea of having to create a button + Go To URL (on click) because the button doesn't appear on all screens/states, etc.

Is there a way to turn the entire project into a button without losing the animation action? i.e. so that no matter what state the banner is in, if someone clicks on it, they go to the URL?

My first piece of advice is not to use Flash Catalyst in the fashion. The reason being, it is built on the Flex framework. This will cause a slight delay while it might be downloaded, then a slight delay while it initializes. The file size also might be an issue if you are planning on publishing the banner into an ad network. They have very strict guideline on file size and bandwidth. If it is for your own site, or a single client, then just be aware of the 'weight' of the project might have an impact on it's usability.

With that said, here is an outline of what you need to do:

You are going to need to rebuild the banner so that instead of all the animations occurring at the top level of the Flash Catalyst project, they are instead wrapped inside a single custom component. Then on this single component you can apply the interaction. Yes it will mean a complete rebuild.

The only other option, would be to include a component at the bottom visible layer that is shared among all the states that has the interaction applied to it. But not knowing the design, this might not work.